Beseler 45MXT illumination problem

Discussion in 'Darkroom Equipment' started by konakoa, Oct 13, 2008.

  1. konakoa

    konakoa Member

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    So, I'm a new Beseler 45MXT owner. I've wanted one for years, and finally got one. Once I got it set up, I noticed right away that something is vignetting the corners of the projected image. (See photo)

    I'm enlarging 4x5 negatives with a 135mm Nikon enlarging lens. My light source is the Dichro 45S color head, with the 4x5 mixing chamber. The upper bellows are as compressed as possible. As best I can determine, it's something with the placement of the negative in relation to the light source.

    So, I figure I could do one of two things:

    1. Try a 150mm enlarging lens. The 135mm I have now is closer to the negative and is 'looking' into the corners and picking up the edges of the light source, or so I think ... A 150, being slightly farther from the negative, might not have as wide of an angle of view.

    2. Swap out the Dichro 45S for a Aristo D2 cold light. The cold light may seat down further and get closer to the negative than the 45S, but I have no way of knowing for sure.

    Anyone else seen anything like this before? I'd greatly appreciate any help or advice.
     
    Last edited by a moderator: Nov 4, 2008
  2. mitch brown

    mitch brown Subscriber

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    hidanny
    see if the head has the right light chamber. i had one that came with a 35 mm chamber and had problems. i got a 4x5 chamber and it worked like a charm.
    mitch
     
  3. Nicholas Lindan

    Nicholas Lindan Advertiser Advertiser

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    My guess is that your guess about the 135mm being a bit short is most likely right.

    If the top platform upon which the light source rests is causing the vignette then changing light sources isn't going to be any help at all.
     
  4. Konical

    Konical Subscriber

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    Good Evening, Danny,

    I can't speak to the characteristics of the Dichro head, since I've used only the standard condenser head.

    Your attached image suggests to me that the negative carrier could be just a bit off-center, although that problem usually would show up in only one or two corners, not three. Could the lens be a bit off-center in its mounting board? Are you using a standard Beseler negative carrier which automatically centers the opening? Some years ago, I used a home-made Masonite carrier for 4 x 5 and had to be very careful with its placement in the negative stage. Consider also that your problem is not really severe. How many negatives would you want to print absolutely full-frame?

    I also use a 135mm lens (a Schneider in my case) for 4 x 5 on my Beseler MCR-X, but have no problem with coverage.

    One note about the head placement: With my condenser head, I deliberately keep it just a little above the indicator mark for 4 x 5 because getting it as low as possible can sometimes bring into partial focus any small smudge or dust mite on the bottom condenser lens. I thereby sacrifice just a very tiny amount of coverage, but this causes no problem since most negatives receive at least some minor cropping.

    Konical
     
  5. 23mjm

    23mjm Member

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    I have the same set up and the 135mm Nikkor lens will cover just fine. I found mine did the same thing when I didn't have the upper bellows scrunched up all the way. Did you take off the little scale on the right side for setting the bellow correctly with the condenser. If i remember that little scale will keep you from scrunching up the bellows enough!!!
     
  6. MurrayMinchin

    MurrayMinchin Membership Council Council

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    Was your photograph taken straight up through the bellows, looking at the light source while the negative carrier was in place? If so, it looks like the light source needs to be 'nudged this way and that' until all four corners are good. Mine has a fair bit of wiggle room where the light source is seated. Good Luck!

    Murray
     
  7. konakoa

    konakoa Member

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    I've tried several of the suggestions posted here (thanks!)

    Of the suggestions you all thought of: I have checked and rechecked the upper bellows. There is a small gap from the bottom of the diffuser to the negative, yet the upper bellows just won't collapse any more. However, this gap seems to be minimal. I tried wiggling the 45S light source back and forth, yet there is essentially no leeway for the light to be moved in the enlarger opening. I am using a brand new Beseler 4x5 negative carrier to mount negatives in the enlarger.

    I removed the entire lens panel assembly on the bottom of the enlarger and crawled under to do some more checking. It would seem my problem is a misaligned light source, or that my negative stage/carrier is way off. What I found is that I can visibly see the edges of the 45S' 4x5 diffuser in the corners of my negative carrier from underneath the enlarger.

    The negative carrier is seated and centered properly. I can't move the 45S light source any appreciable amount within the enlarger. Something must not be aligned properly. I know of, and have adjusted, the lower negative stage and the lens panel as part of the alignment process (each can be tilted on both axis to get everything parallel) but neither can be shifted as far as I can see.

    Has anyone run into this before?
     
    Last edited by a moderator: Nov 4, 2008
  8. konakoa

    konakoa Member

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    Konical, thanks for your posting. I was chewing on what you said for awhile. Yes, I could just crop a little. Yet when I compose the image on the ground glass of my camera, I know I'll be losing a little in the corners as the film is just a bit smaller than what I see in the camera. Then the negative carrier of the enlarger eats a little more of the image. Still more to the edges of the paper easel. If the resulting print is pretty good, I'll drymount or cut a mat for it, and lose yet even more along the edges.

    I know this is minor, yet I feel that all the involuntary cropping is eating away at my photographs. To have my enlarger take yet another bite out of my photos (when it doesn't have to) bothers me some.
     
  9. grahamp

    grahamp Subscriber

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    I have an older model chassis with the same head and a 135mm Schneider 5.6 lens. This works fine for 5x4.

    Make sure you have the 5x4 mixing chamber, and that the internals are all lined up. You should be able to check this by looking at the light intensity with the head off.

    There are no condensers between the light source and the negative.

    With the head and lens off, test the alignment. Drop a plumb line down the center through the lens panel. If your carrier is glassless, put that in. That should confirm that everything is in approximate center.

    Reassemble. Focus the edges of the carrier, and draw a diagram on the baseboard. Take the carrier out. The light spread should be evenly larger than the carrier image.
     
  10. Resoman

    Resoman Member

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    I've never used that particular Beseler enlarger, but I can attest that the EL-Nikkor 135 has no problem covering the entire 4x5 negative on my LPL enlarger. It's hard to imagine that the Beseler is designed in such a way that one has to use a 150mm lens to cover the entire neg. There's gotta be a solution, I would think.

    In any case, I'd be quite unhappy if my equipment was forcing me to crop my prints in order to hide its shortcomings.

    Gary,

    East Snook, TX
     
  11. konakoa

    konakoa Member

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    Well, it appeared that my problem was my old Dichro 45S light source after all. I went through all the recommendations posted here earlier once more (even the plumb line) before I finally just replaced the light source with a new Aristo D2 cold light.

    Both light sources measure 6 1/4" across at the diffuser. However, the Aristo visibly seats down further/deeper into the enlarger than the 45S does, and the problem I was having with the corners of the 4x5 film carrier not being illuminated went away.

    I don't think this problem was intentional; my thinking is that something somewhere in the design or materials must have changed between the time my 45S was made and when my 45MXT enlarger was manufactured. I've read in a few places that the bellows material of the MXT is thicker than previous enlargers (it won't compress as much), and I can see that my MXT has a foam light seal on the negative stage (not present on the older enlargers) that is adding a little more space between the light source and film.

    So, with the new closer light source my enlarger works great now. Woot!
     
    Last edited by a moderator: Nov 4, 2008
  12. jeroldharter

    jeroldharter Member

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    Could it have been the lens board as well? Sometimes I think the 150 mm lenses require a little extension cone on the lens board.
     
  13. konakoa

    konakoa Member

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    Jerold, I'm certain it was the light source all along, not the lens.

    I don't think Beseler makes a extension cone (please correct me if I'm wrong) as they're just not needed. The bellows on my MXT are fairly long -- I just measured about 11" of extension from the negative to the top of the lens. I'm barely using half of that for my 135mm lens, so I doubt a 150mm lens would be a problem either. :smile: